The present invention relates to storage devices. In particular, the present invention relates to suspension assemblies in storage devices.
In data storage devices, data is typically stored in tracks on a medium. To access the data, a head is positioned within a track while the medium moves beneath the head.
In many data storage devices, the head is positioned by an actuator assembly that includes a motor that rotates one or more actuator arms. Each actuator arm supports one or two suspensions that each support a head/gimbal assembly. Typically, a suspension includes three distinct areas: a base plate area that connects to the actuator arm, a spring area that provides a vertical spring force to bias the head toward the medium, and a load beam that extends from the spring area to the head/gimbal assembly. The spring force provided by the suspension is designed to allow the head to follow height variations on the surface of the medium without impacting the medium or moving too far away from the medium.
In the past, suspensions have typically been formed from sheets of stainless steel. In some prior art systems, using sheets of stainless steel results in a suspension in which the spring area and the load beam are the same thickness. Because of this, both areas exhibit similar mechanical properties. However, because the spring area and the load beam perform different functions, it is desirable that they have different mechanical properties. In particular, it is desirable that the spring area be more elastic or flexible than the load beam because a load beam that is too elastic will tend to bend and resonate in response to windage induced forces.
To solve this problem, the prior art has developed several techniques for forming a suspension so that the thickness of the spring area is less than the thickness of the load beam. In one technique, the spring area is partially etched to reduce its thickness. However, partial etching provides poor thickness control of the partially etched portions and results in poor pre-load stability in the spring area. A second technique welds a second metal sheet to the load beam. However, welding is costly and causes distortion of the load beam due to the heating of the metal. In addition, welding requires a minimum surface area that will not be present in smaller suspensions of the future.
A third technique taught by the art is to form the suspension through lamination. For example, U.S. Pat. No. 4,996,623 to Erpelding et al. discloses a suspension formed about a flat flexible material. In the base area and the load beam, the flat flexible material is bonded on both sides to patterned metal layers. However in the spring area, the flat flexible material is only bonded on one side to a metal layer. This makes the spring area more flexible than the base area and the load beam.
Although the spring area is more flexible than the load beam in Erpelding, it is still formed of two different material layers. In addition, the laminated structures of the past do not aid in the manufacture or installation of the suspension. In particular, the laminated structures of the past do not aid in rail formation, welding the suspension to a base plate, aligning the suspension with other pieces, attaching a flex electrical circuit to the suspension, or attaching micromotors such as piezo-electric elements to the suspension.
The present invention provides a solution to these and other problems, and offers other advantages over the prior art.
A laminated suspension includes recesses in one layer of the suspension that aid in attaching elements to the suspension and in utilizing a micromotor placed on the suspension. In particular, examples of the recesses include weld areas for welding the suspension to other items, fiducials that are used to align the suspension with other items, micromotor recesses that receive micromotors, adhesive controls that restrict the location of adhesives on the suspension, electrical interconnect attachment tabs that accept flex circuits, side rails that reduce torsional resonance during microactuation and microactuator hinges that reduce the force needed for microactuation. In addition, a laminated suspension with a single metal layer in the spring area is provided.
These and various other features as well as advantages which characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.